MoS2/Graphene Heterostructures as Gas Sensors for CO, CO2, NO and HF

The strategic integration of the tunable band gap and high carrier mobility of MoS2 with the exceptional electrical conductivity of graphene offers a compelling route to circumvent the intrinsic sensing limitations of each material in isolation. Within the resulting van der Waals heterostructures, synergistic interlayer electronic coupling substantially reshapes the optoelectronic response. In particular, the MoS2/graphene interface exhibits an ultraviolet absorption coefficient of approximately 3.5 × 105 cm−1 at 350 nm, an enhancement of about 20% relative to pristine MoS2. First-principles density functional theory (DFT) calculations further show that tuning the interlayer spacing induces a finite band gap in graphene, attaining 67.8 meV at a compressed separation of 2.3 Å. Building on these electronic insights, the gas-sensing performance of the MoS2/graphene heterostructure was evaluated toward CO, CO2, NO, and HF gases. The adsorption energies, supported by electronegativity analysis, were consistently negative for oxidizing (CO2, NO), reducing (CO), and corrosive (HF) molecules, namely −70 meV, −51 meV, −363 meV, and −127 meV for CO, CO2, NO, and HF, respectively, a trend corroborated by electronegativity analysis. This energetically favorable adsorption underscores the strong gas–surface interactions enabled by the heterointerface, revealing a superior sensing response compared to either MoS2 or graphene alone. These results highlight the promising potential of MoS2/graphene heterostructures for next-generation, high-sensitivity gas-monitoring technologies.